Rectifier assembly



NOV. 13, L, Kl HEDDING EVAL RECTIFIER ASSEMBLY Filed June 24, 1949 2 SHEETS- SHEET 1 INVENTORS. Limpie Ii'. Bedding and 5 H ZewO BY g FHF/R A TTRNEY NOV. 13, 1951 1 K HEDDlNG ETAL I 2,574,783

RECTIFIER ASSEMBLY 2 SHEETS-SHEET 2 Filed June 24, 1949 Figi l0.

l JNVENTORS. LLnnie I Hedd 17g sHZe'a/o lgt IZ THEIR ATTORNEY Patented Nov. 13, 1951 RECTIFIER! AS SEMBLY Linnie K. Hedding, Wilkinsburg, and Regis H.

Zetwo.. Swissvale, Pa., assignors to Westinghouse Aix:- Brake` Com Pennsylvania pany, a corporation of Application June 24, 1949SeriaLNo. 101,014.

18iClaims. 1

Our invention relates toelectric rectier assemblies of the stackedV disc type, and particularly to anassembly ofsuch rectiiierswhichv is usable in a circuit-where rectiers ofv diierent current-carrying capacities are required.

Power supply systems` for charging both the A and B batteries-of` a radioreceiver havebeen proposed. Because of the different characteris tics of theA andi Bbatter-ies, the rectifierv for the Abattery is required to have relatively high current and low voltage characteristics, While the rectifier for the B battery is required to'have relatively high. voltage and lowy current char..- acteristics. These battery charging circuitsheretofore. proposed may includer a` transformer. and a condenser, for. purposesA described therein.

Iti is therefore an. object of: our' present invention to provide an improved assembly of rectiiier elements including portions. of` different-current carrying capacities.

Another object istov provide improved means for spring loading a stack. ofA rectifier elements so as to maintain all the. elements underV pressure, thereby reducing. the contact resistance he.- tween the surfacesof the rectiers.

Another object is to provide anY improved termi'- nal construction for such assemblies.

A further object is toprovide. such any assembly which is compact and easily assembled'J from'. its component parts.

Another Objectis toprovide. an improvedv unit including arectier stack assembly, av transformer, and a condenser.

We accomplish the foregoing andV other ob.- jects of our inventionby providing amoldedplas.- tic housing having. aligned compartments. of. dif;- ferent cross-sectional areas. A long stack: of small area elements is providedy in the smaller of the two :compartments and a shorter stack of wider area elements in the. larger. compartment. The two stacks are heldin compression by the.y same spring, loading arrangement, several modications of which are.- shown. Several;y dif'- ferent terminal arrangements are. shown, each involving the use of terminal discs which are stacked with the rectiiier elements and project in various ways to the outsideof the casing.y In certain modifications ofour inventiozrthe termi nal lugs are arranged so as to project through suitable apertures providedin thecasing, through which the lugs are inserted during. assembly.

Two modifications of combinationl units are shown, wherein a rectifier stack assembly ofthe type described is combined with acondenser and a transformer for usein a battery charging. circuit.

cross-sectional View of another form of' rectifier 2. We shallV describe several forms of rectifier assemblies embodying our invention, and shall then point out the novel features thereof in claims.

In the drawings, Fig. l is a cross-sectional view of one form of rectifier stack assembly embodying certain features of. our invention. Fig. 2 is a cross-sectional view, taken on the line II-II of Fig. 4, looking in the direction of the arrows, of a combined rectier, transformer, and condenser unit embodying certain features of our invention. Fig. 3' is another cross-sectional view of the unit shown in Fig. 2,v taken along the lines III-III of Figs. 2 and'4, looking in the direction of the arrows. Fig. l is a bottom View' of the combined unit shown in Figs. 2 and'3. Fig. 5 is a stack assembly embodying our invention. Fig. 6 is a wiring diagram of'a battery charging circuit with which our invention may be used. Fig. 7 is a cross-sectionalV view of a, modified' form o f rectifier stack assembly embodying certain features of our` invention. Fig. 8'is a bottom plan view of the assembly shown in Fig. 7. Fig. 9 is a top plan view' of' the assembly shown in Fig. 7. Fig. 10 is a cross-sectional' view, taken along the line X-X of Fig. 12, of another :form of,- combined rectifier, transformer, and' condenser unit embodying our invention'. Fig; 1'1' is an elevational view'of the' unit shown in Fig. 1'0, taken from the right-hand' side ofthe unitV as` ity appears in Fig. 10; Fig. l2'is a bottom plan View of the unit shown in Figs'. 10-and 11;

Similar reference characters refer tosimilar parts in each ofthe several views;

There' is shown' at' I' a hollow, generally cylindrical casing of'molded insulating material. The casing Iy has av relativelyI narrow portion la and a. relatively wide portion Ibseparated by a shoulder Ic. A compartment 2 is formed inside the narrow portion la ofthe casing I TheV compartment 2- is closed at its 'upper'end and opens at its lower end intoav larger compartment 3 formed inside the-wide portion IIJ-ofv the casing.

Inside the-compartment 2y is a stack of rectifier elements 4', which may be of the selenium, copper oxide, or other suitable type- As shown, these elements are of' the selenium type, and each comprises a short metalbase 4a, a selenium composition layer dbandfa counterelectrodelayer'4'c. Thethickness of the'layers 4b and 4c has been exaggerated'. in. the. drawing to make. the

structure clear. Aterminali disc 5, of suitable electrically conducting` materiah rests onY the uppermost one of the rectifier elements 4. The

atteste terminal disc is provided with an upwardly projecting terminal lug 5a which extends through an opening id, formed in the top or the casing I. A coil spring 3 is held in compression between the top of the casing I and the terminal disc 5. The lowest rectier element 4 rests on a spacer block which lies partly in the compartment and partly in the compartment 3. Under the block l is a terminal disc 8, having a terminal lug 8a which projects through a suitable aperture Ie in the casing I. The terminal disc 8 rests on an insulating disc 9. -k

Below the disc 9 is a second rectier stack comprising a single rectifier element Itl between terminal discs iI and I2. The element I, like the element Il, comprises a base Illa, a selenium composition layer Il'b and a counterelectrode layer itc. The terminal discs il and i2 are provided with lugs Ila and 12a corresponding to the lug 3a on disc 8.- Lugs IIa and I2a. also project through apertures le in the casing I. The lower end of compartment 3 is closed by an insulating closure disc I3 held-'in place by a concave spring disc I; The spring disc Id is made so that its free diameter is somewhat greater than the internal diameter of the compartment 3. When the spring disc Ill is pushed into the compartment 3, it yields, its center bulging upwardly so that it contracts sufficiently to pass into the compartment 3. After being released, it again expands, and its edges bite into the casing vI and prevent the withdrawal of the spring disc ill or the other parts of the assembly from the casing I.

The arrangement shown in Fig. 1 may be constructed by inserting the component parts in the proper order through the bottom of the casing I. After assembly, all the rectier elements, terminal discs, and the spacer block are held in compression between the coil spring 6 and the disc spring lli'. This maintains the several rectifier elements and terminal discs in good electrical contact with each other. The apertures Id and le may then be sealed with a suitable sealing material.

It should be noted that the dimensions of the rectifier elements' d, spacer block "i, springV 6', Y'andmthe compartment 2 are such that the spacer block i lies partly in the compartment 2 and partly in compartment 3. The block Y'I is then .eective to keep the edge portion'o'f the terminal disc' from resting'against the internal surface of the shoulder Ic. If the edge of the terminal disc 8 were permitted to rest against the shoulder Ic, then the spring pressure available to hold the rectifier lparts in rcontact would be diifer'ent, and hence might lead to erratic operation of the rectiiers.

Since the rectifier elements 4 are of relatively small area, their current-carrying capacity is low. However, since several of these rectifier velements are stacked von top of one another, the voltage` characteristic of, the complete stack is comparatively high. The element I is made wider, so that its current-carrying capacity is much greater than that of the stack 4. Furthermore, only one rectifier element I0 is provided, so that the voltage drop between the terminals of the lower stack is relatively low. It will be recognized that the assembly shown is readily adaptable to other current and voltage requirements by changing the number of rectifier elements in either of the stacks or bychanging the .size of the elements used. -Y Y f U Figures 2 to 4 There is shown in these gures a combined unit including a rectifier stack assembly generally indicated at l5, a transformer it, and a condenser I'. The combined unit is supported on a molded insulating base I8, of a box-like formation, open at the top, and provided at its opposite sides with mounting lugs ISa. A pair of brackets I9 are attached to the opposite walls of the base I8 nearest their upper edges. Transformer I6 has a winding ia, and a core Ib i lwhich is supported on the brackets i9.

The base I8 is provided with two aligned compartments 20 and 2I for receiving the rectier stack assembly I5. The compartments 2li and 2l correspond generally to the compartments 2 and 3 of Fig. 1.

The rectifier stack assembly I5 is mounted on .its side,.with the rectifier elements standing on edge. l, The stack assembly I5, as best seen in Fig. 2, comprises a low current high voltage stack of elements li having a terminal disc 22 at the closed end of the compartment 2B and a terminal disc 23 near the opposite end of the compartment 20. A The rectifier assembly I5 also includes a high current, low voltage stack which comprisesl a single rectier element Il), a terminal disc 24 to the left of the rectier element, and a terminal discY 25 to the right. of the element. A coil spring 21 is held in compression between the terminal discs 23.and 24, and serves to hold the elements of both stacks in contact under pressure. An insulating disc 28 is provided between terminal disc 23 and spring 21. f Y The compartments 20 and 2I are open at the top, as they appear in the drawings, or at the sides, considering them with respect to the axis of the cylindrical stack. The rectier elements, terminal discs, and spring 21 may be assembled in the compartments .20 and 2! by insertion through the open top of. these compartments. TheV terminal discs 22 and 24 areprovided with downwardly projecting terminal lugs 22a and Zlia which extend through suitable openings in the base I8 downwardlyto 'a point where they are accessible from the exterior of the unit.

A coverplate 29- is provided vfor the compartments 20 and ZI. The terminal discs 23 and 25 are provided with upwardly projecting terminal lugs 23a and 25a which pass through suitable terminal lugs apertured in the .coverplate 2.9,.so

that the plate 29;may beslipped on over the lugs 2-3a' and 25a. afterv the rectifier stack has been assembled inthe compartments 2@ and 2l. The cover-plate 29is heldin place.. on the base i8 by 'means of a screw 3i);Y which also holds a linger 3.! forl retaining the condenser I1 in place within the box-like base I8.

Additional openings are provided in the bottomofthe base I8 for receiving bushings 32 which carry wires from the interior of the enclosure formed by base vI8 and its cover 33. Y

Figure 5 There is shown in Fig. 5 a rectifier stack assem- `bly having somewhat different terminal arrangements. In particular, the terminal arrangements Yprovided for the high current rectifier stack are so constructed as to give that stack an exceptionally high current-carrying capacity.

-'-The rectifier stack assembly of Fig. 5 is envclosed aVcaSiIigV 34, which'is generally similar tothe-casing 'of Fig.' l, except for certain details which will be specifically mentioned below. The

the rectier stack assembly of Fig. 1.

sembl'y includes a casing 42 of generally cylin 5 casing 34 encloses` a= stack ofrectierelements 4; a spacer block 1, a closure block` I3', and a spring disc I4', all of which-correspond generally to the similarly numbered` elements of Fig. 1.

. Above the uppermost. element 4 is. provided a terminal disc 35` having an upstruck lug 35apro.- jecting upward neary its center through a suit.- ablev terminal lug aperture provided. in the end of casing 3.4. This aperture. may of course be sealed by. suitable Asealing material after the stacksr are assembled..

Thev high. current-carrying capacity stack shown in Fig. 5 between the. spacer block 'I and the closure block I3: -comprises three rectier elements.v I0. separated from eachA other and from the blocks I and I3` by terminaldiscs.. Each of thev discs 36` is. provided with a. terminal. lug 36a or 36h. The lugs 35a and 365`l are arranged during assembly so that alternate lugs project from opposite sides ofthe stack. All therlugs projecting. from one side of the stack are electrically connected. As shown in ther drawings, the lugs may be bent over to engage each other and are soldered at their point of contact. The arrangement is such that all the rectifier elements I are electrically in parallel between the connected terminals 36a at the left of the drawings and the connected terminals 36h at the right of the drawings. It may therefore be seen that the currentcarrying capacity 0f this stack assembly is that of the three elements I@ in parallel. While in the modification shown, three elements are connected in parallel, it will be readily understood that. by usingV the same principles of construction three or more stacks of elements could be connected in parallel. Fig. may be considered as showing three stacks in parallel, each stack consisting of one element.

The casing 34 is provided with slots 34a at its opposite sides to permit assembly of the terminal discs 3SY and their projecting lugs. assembly, these slots 34a may be sealed with suitable sealing material.

In the assembly shown inv Fig. 5, the compression spring such as that shownv at 6 in Fig. l, is omitted, and the spring disc I4 alone holds the elements of the rectier'stacks in electrical contact.

It may be seen that the two rectier stacks of Fig. 5 have only three. terminals, 35a, 35a, and 36h. The terminal 36a isY common to both the upperA stack andthe lower stack.l Such anarrangement may be used in` connection with. a battery charging circuit such as that shown in Fig. 6. In that figure, alternating current from .thesecondary of a transformer 31 flows through a rectifier 38, which corresponds to the lower stack in Fig. 5, to-charge an A battery 39. Current also ows from the same secondary winding through a rectier 4B, which corresponds to the upper stack in Fig. 5, to charge a B battery 4I. The terminals 35a, 36a, andb are shown diagrammatically in Fig. 6.

Since the lugv 35a projects througha central aperture in the casing, the angular position of disc 3.5 during assembly is not critical. Hence assembly is easier than is the case when the lug must be aligned with an aperture spaced from the center, as in the case of lug 5a and aperture Id of Fig. 1, for example.

Figures 7 to 9 These iigures illustrate another form of'rectier stack assembly corresponding generally to Thisfv-as- After drical form, having a narrow portion 42a. and a wide. portion 421; separated by a shoulder 42e. The. casing 42 is hollow and its upper end isr closed by a heavy terminal disc 43 molded inethecasing a short. distance below its upper end. A terminal lug. 44. is attached to the disc 43, as by brazing, before the molding operation, so that lug 44 is also. molded in the casing 42. The end of terminalz lug` 44. projects outwardly of the casing 42 ina` generally radial direction just above the shoulder 42e.

The. rectifier elements 4, the spacer block 'I, the rectier element I0, and the terminal discs II and I2. correspondr generally to the similarly numbered elements in Fig. 1. The only substantial diierence is that the terminal lugs I Ib and I2bon the discs II and I2 have their ends bent over after assembly so that they extend parallel to the surface of the shoulder 42e. It will be remembered that. the corresponding terminal lugs IIa and I2a of Fig. 1 extended parallel to the axis of the casing I'. The casing 42 is provided with recesses 42d leading into apertures 42e to receive the terminal lugs I I'b and I2b during assembly of the rectier stacks.

A concave spring disc 45 closes the lower end of the casing 42 and also holds the two rectier stacksin compression. The spring disc 45 is provided witha pair of diametrically opposite wings 45a, and the casing 42. is provided with a pair of diametrically opposite projections 42j. These parts are best shown in Fig. 8. When the stacks are assembled, the disc 45 is pushed through the opening at the lower end of casing 42 with the wings 45a at right angles to the position shown in Fig. 8. After the wings 45a have been pushed pastA the projections 42], the disc 45 is rotated through degrees to bring the wings 45a back behind the projections 427, which thereby maintain the disc 45 in place.

The lower end of casing 42' is provided with a pair of diametrically opposite legs 46 which serve to support the casing. The legs 45 extend downwardly beyond the lower surface of the other parts of casing 42, so that the casing 42 is supported slightly above whatever surface the legs 45 may be attached to. This permits a circulation of air past the spring disc 45 and serves to cool the rectier assembly in case it heats up due to the current ow therethrough. The terminal disc 43 at the upper end of the assembly also serves to dissipate heat from the rectifier stacks. It should be noted that by virtue of the construction of the upper end of casing 42, the terminal disc 43 is recessed below the outer surface of the casing and is thereby protected against accidental electrical contact. The spring disc 45, which is in electrical contact with terminal disc I2 to provide better heat conduction, is similarly recessed in the casing to protect it from accidental electrical contact.

Figures-10 to 12 These gures show a diiferent form of combined unit similar to that of Figs. 2 toe, and including a transformer 5I, a condenser 49, and a rectier stack assembly 50. Transformer 5I is provided witha core 52 and a winding 53.

The three principal elements in the combined unit are supported on a box-like base 54, of molded insulating material. Threaded metallic inserts, 55 are molded into the upper surfaces of the sides of base 54 at opposite points. The transformer core 52 has its ends resting on these upper surfaces of the base 54. The core 52 is held onl the-base 54'by meanslof bolts 56, whose lower aanwas ends are received inthe threaded inserts 55. Ihe bolts 56 also hold a cover 51 in place on the transformer. The condenser 49 rests on the transformer winding 53 and is enclosed by the cover 51. The molded base 54 is made hollow at one end to form two vertically aligned cylindrical compartments 58 and 59, which correspond generally to the compartments 2 and 3 of Fig. 1, and which house the rectifier assembly 50. The compartment 58 encloses a stack of rectier elements 4 of relatively low current-carrying capacity, and the compartment 59 houses a stack comprising a single element I6 of relatively high currentcarrying capacity. At the upper end of the compartment 58, a terminal disc 65 is molded into the base 54. The terminal disc 66 is provided with a terminal lug KillaV which projects through the Walls of compartment 58 into the space within the base 54. A compression spring 6 is retained between the terminal disc 60 and the uppermost rectier element 4. A pair of terminal discs 6l is located above and below the rectiiier element l0. The discs 6I are provided with projecting terminal lugs 6 la which extend through a suitable opening 54af in the4 wall of compartment 59 into the space within `the base 54. The terminal discs 6I are inserted into the compartment 59 through its open bottom during assembly of the rectier stack. A

spacer block 1 is located between the lowest elez:

ment 4 and the upper surface of the upper terminal disc 6|. The lower side of the compartment 59, which is left open during manufacture of the base 54 so that the rectifier stacks may be assembled through it, is closed after the stacks are assembled by closure plate 62, also of insulating material, which may be sealed in place by any well-known means. After the rectier stacks are assembled, the opening 54a may also be sealed with any suitable sealing material.

The bottom of the base 54 is provided with a number of metal rivets 63 onto which are soldered wires from inside the base for making electrical connections to outer terminals 64.

Although we have herein shown and described only a few forms of rectiiier assemblies embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we Vclaim is:

1. A rectifier assembly having a low current portion and a high current portion comprising a g casing having aligned openings of different crosssectional areas, a low current rectifier stack including at least one rectiiier element in the opening of smaller area, a high current rectifier stack including at least one rectifier element in the opening of smaller area, a stack of rectifier elements of high currentcarrying capacity received in the opening of larger area, anda spring in the casing holding the flat faces of the elements of both stacks in contact.

43. A rectifier assemblyhaving a low current :portionand a high currentportion, comprising a casing havinga rst compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area which is closed at its opposite end, a coinpression spring at .the closed end of one of said compartments, a low current rectifier stack including at least one rectier element in said rst compartment, a high current rectifier stack including at least one rectiiier element in the second compartment, and a spacer block in said first compartment at the end thereof adjacent to the second compartment, the relative lengths of the spring, stacks and block being such that the block projects only partly into the second compartment, said spring being effective to hold the elements of both stacks in compression.

4. A rectifier assembly having a low current portion and a high current portion, comprising a casing having a iirst compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area which is closed at its opposite end, a low current rectiiier stack including at least one rectifier element in said rst compartment, a spacer block in said iirst compartment at the end thereof adjacent to the second compartment, the combined length of the stack and block being such that the block projects only partly into the second compartment, and a high current rectier stack including at least one rectifier element in the second compartment, and a compression spring at the closed end of said second compartment, said spring being effective to hold the elements of both stacks in compression.

5. A rectifier assembly having a low current portion and a high current portion, comprising a casing having a first compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectioal area which is closed at its opposite end, a compression spring in the closed end of the first compartment, a low current rectifier stack including at least one rectifier element in said rst compartment, a spacer block in said iirst compartment at the end thereof adjacent to the second compartment, the combined length of the spring, stack and block being such that the block projects only partly into the second compartment, and a high current rectifier stack including at least one rectifier element in the second compartment between the block and the closed end of said second compartment, said spring being eiective to hold the elements of both stacks in compression.

6. A rectifier assembly having a low current portion and a high current portion comprising a casing having a first compartment therein closed at one end and opening at the other endy into a second compartment of larger cross-sectional area, a low current rectifier stack including at least one rectifier element in said first compartment, a high current rectifier stack including at least one rectifier element in said second compartment, said casing having an opening to give access to said compartments for assembly of said stacks therein, a closure for said opening, and means holding the elements of both stacks in longitudinal compression.

` 7. A rectifier assembly having a low current portion and a high current portion comprising a casing having a rst compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area, a low current rectifier stackincluding at least one rectierelement in said iirst coinpartment, a high current rectifier stack vincluding at least'one rectifier element in said second compartment, said ycasing having an opening at one side of said compartments to give access to said compartments 'for assembly of said stacks therein, means holding :the elements of both stacks in longitudinal compression, and a closure element blocking said opening.

8. A rectifier assembly having a lovv current portion and a high current portion comprising a casing having a first compartment therein closed at one end and opening at th'e other end into a second'compartm'ent of larger cross-sectional area, a low current rectifier stack including at least one rectifier element Yin said first compartment, a high current rectifier stack including at least one rectifier element in 'said second compartment, said `casing having an opening at the end of said second compartment opposite said first compartment to give access to said compartments for assembly of said stacks therein, and means holding the elements of both stacks in longitudinal compression, comprising a yieldable closure element larger than said opening and Wedgable therein 'to close the opening.

9. A rectifier assembly having a low current portion and a high current portion comprising a casing having Aa first compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area, a low current rectifier stack including at least one rectifier element in said first compartment, a high current 'rectiiier stack including at least one rectifier .element in said second compartment, said casing having an aperture at the end of said second compartment opposite said rst compartmentto give access to said compartments for assembly of said stacks therein, and a closure element for closing said aperture, said housing and said closure element having projecting lugs adapted to interlock upon insertion of the closure element .into the aperture and rotation of the element in the aperture, said closure element being effective when said lugs are so interlocked to close the aperture.

10. A rectifier assembly having a lovv current portion and a high current portion comprising a casing having a first compartment therein closed at one end and opening at the other end into a second compartment .of larger cross-secf tional area, a low current rectifier stack including at least one rectifier element in said first compartment, a high current rectifier stack including at least one rectifier v`element in said second compartment, a spring in the casing holding the fiat faces of the elements of both stacks in electrical contact, said casing having an aperture at the end of said second compartment opposite said 'first compartment to give access to said compartments for assembly of said stacks therein, and a yieldable closure element larger than said aperture and Wedgable therein to close the aperture, said closure element being effective when in place to aid said spring in holding the elements of both rectifier stacks in compression.

11. A rectifier assembly having portions of different current-carrying capacities, comprising a casing having a first compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area which is closed at its opposite end, a low current rectifier stack including at least one rectifler element in said first compartment, a high current rectifier stack including at least one recthier element in the second compartment, a first :terminaldisc at the closed end of the first compartment, a second terminal disc at the closed end of the second compartment, and a third terminal ydisc at the inner end of the second stack, a terminal lug on each of said terminal discs, said lugs projecting through the casing to the outside thereof, and means holding the rectifier stacks and the terminal'discs in contact.

12. A rectifier assembly having portions of different current-carrying capacities, comprising a casing having a first compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area, a lovv current rectifier stack including at least one rectifier element in said first compartment, a high current rectifier stack including at least one rectifier element in the second compartment, a first terminal disc at the closed end of the first compartment, second and third terminal discs at the opposite ends of the high current rectifier stack, a terminal lug on each of said terminal discs, said lugs being adapted to project outside said casing, said casing having an opening at the end of said second compartment opposite said flrst compartment to give access to said compartments for assembly of the stacks and terminal discs therein, a closure for said opening, the lugs on said second and said third discs extending at right angles to the discs, said casing having two circumferentially spaced terminal lug apertures in the end of said second compartment nearest said first compartment and adapted to receive the lugs on said second and third discs as the discs are assembled so that said lugs project through said lug apertures, and means holding the rectier elements and the terminal discs in electrical contact.

13. A rectifier assembly having portions of different current-carrying capacities, comprising a casing having a rst compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area, a low current rectifier stack including at least one rectifier element in said first compartment, a high current rectifier stack including at least one rectifier element inthe second cornpartment, a first terminal disc at the closed end of the first compartment, a second and a third terminal disc at the 'opposite ends of the high current rectifier stack, a terminal lug on each of said terminal discs, said lugs being adapted to project outside said casing, said casing having an opening at the end of said second compartment opposite said first compartment to give access to said compartments for assembly of the stacks and terminal discs therein, a closure for said opening, the lug on said first disc being struck up at right angles to the disc near its center, said casing having a terminal lug aperture adapted to receive said one lug as said disc is assembled so that said one lug projects through said lug aperture, and means holding the rectifier elements and the terminal discs in electrical contact.

14. A rectifier assembly having portions of different current-carrying capacities, comprising a casing having a first compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area, a low current rectifier stack including at least one rectifier element in said first compartment, a high current rectifier stack including at least one rectifier element in the second compartment, a first terminal disc at the closed end of the rst compartment, a second terminal disc at Va third terminal disc at the inner end of the second stack, arterminal lug on each of said terminal discs, said lugs being adapted to project outside said casing when said discs are assembled, a spring in the casing holding the elements of both stacks and the terminal discs in electrical contact, said casing having an aperture to give access to said compartments for assembly ofv the stacks therein, and a closure element for closing said aperture.

15.fA rectifier assembly having portions of different current-carrying capacities, comprising a` casing having a first compartment therein closed at one end and opening at the other end into a second compartment of larger cross-sectional area, a low current rectifier stack includ- .ing at least one rectifier element in said first compartment, a high current rectifier stack including at least one rectifier element in the second compartment, a first and a second terminal disc at the opposite ends of the low current rectifierv stack, third and fourth terminal discs at'the oposite ends of the `high current rectier stack, a terminal lug on each of said terminal discs, an insulation member between said stacks, said casing having an opening at the end ofthe second compartment opposite said first compartment to give access to said compartments for assembly of the stacks and terminal discs therein, a closure for said opening, each one of said lugs extending at right angles to its supporting disc, said casing having a terminal lug aperture to receive each one of said lugs as vthe respective disc is assembled so that the lug projects through said lug aperture, and means holding the rectiiier elements and the terminal discs in electrical contact.

16. A rectifier assembly having portions of different current-carrying capacities, comprising a casing having a first compartment therein closed at one end and opening at the other end intoV a second compartment of larger cross-sectional area, a low current rectifier stack including at least "one rectifier element in said first compartment, a high current rectifier stack including at least one rectier element in the second compartment, a first and a second terminal disc` the lugs as the discs are assembled, said closure having terminal lug apertures to receive others of the lugs as the closure is put in place, and means holding the rectifier elements and the terminal discs in electrical contact.

17. A rectifier assembly having portions of dilierent current-carrying capacities, comprising a molded casing of insulating material having a first compartment formed therein, a metal disc molded in said casing and closing one end of said compartment, said disc having its outer surface exposed so as to radiate heat and recessed in said casing so as to be protected against electrical contact, said first compartment opening at the other end into a second compartment of larger cross-sectional area which is closed at its oposite end, a low current rectifier stack including at least one rectifier element in said first compartment, a high current rectiiier stack including at least one rectifier element in the second compartment, said casing having an opening at the end of said second compartment opposite said first compartment to give access to said compartments for .assembly of said stacks therein, means holding saidvrectiiier elements in electrical contact with each other and with said metal disc, comprising a metallic closure element blocking said opening, and a pair of supporting legs formed on said casing on opposite sides of said opening and extending below said opening so as to permit circulation of air past said metallic closure.

18. An electric rectifier assembly including a box-like base of insulating material open at the top and formed with twoV aligned compartments of different cross-sectional areas, a transformer having a core and a Winding on the core, means for attaching the core tothe sides of said base so that said transformer bridges the base, a rectier stack assembly of relatively low current-carrying Vcapacity in the smaller of said two compartments, a rectifier stack assembly of relatively highcurrent-carrying capacity in the larger of the two compartments, a cover for the base forming therewith an enclosure for said transformer, and a condenserin said enclosure. i 1

LINNIE K. HEDDING. REGIS. H. ZETWO.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 2,491,031 Burgess Dec. 13, 1949 

